There are numerous methods known in the art to disintegrate solid materials and deposits on surfaces, and many such methods include mechanical disintegration. While mechanical disintegration can be conceptually relatively simple, it often requires an operator in close proximity to the solid material or deposits, which may be particularly undesirable where the solid material or deposit is located in a hazardous environment (e.g., inside a coking vessel).
To circumvent at least some of the problems with disintegration of solid materials or deposits in hazardous environments, remote mechanical disintegration, preferably hydraulic cutting may be employed. For example, Novy describes in U.S. Pat. No. 3,880,359 (Apr. 29, 1975), which is incorporated by reference herein, a hydraulic cutting device that is employed in a preformed channel in a coking vessel. Novy's device effectively cuts the coke to allow removal of the coke from the drum, however, requires a preformed channel in which the cutting device operates.
Combined cutting devices have been developed that utilize drill heads, which perform both boring to form a channel and hydraulic cutting as disclosed in U.S. Pat. No. 4,611,613 to Kaplan (Sep. 16, 1986), U.S. Pat. No. 4,673,442 to Kaplan (Jun. 16, 1987), and U.S. Pat. No. 4,738,399 to Adams (Apr. 19, 1988), all of which are incorporated by reference herein. Although such combined cutting devices significantly improve a decoking operation, several disadvantages, particularly relating to the safety of the operator of hydraulic cutting devices still remain.
Among other things, the operator of the hydraulic cutting device is potentially exposed to the high-pressure fluid jet when the drill head is retrieved from the coking vessel (see Prior Art FIG. 1), and such exposure has resulted in several fatalities. In order to avoid potential exposure to the high-pressure fluid jet, automatic shut-off systems have been developed that cut off fluid supply to the drill head when the drill head is retrieved from the coking vessel or other containment. Although interrupting the fluid flow to the drill head is conceptually simple, such mechanisms provide only limited protection to the operator, especially when the fluid interrupt is defective.
Alternatively, insertion and retrieval of the drill head may be performed by the operator from a remote position. A remote position typically ensures safety of the operator, however, tends to be impracticable in many situations, especially when misalignment between the drill head/drill stem and the coking vessel occurs. In a further alternative method, the operator may temporarily move behind a protecting wall when the drill head is inserted and/or removed from the vessel, however, similar difficulties as with remote operation still remain.
Although various apparatus and methods for protection from high-pressure fluid jets are known in the, all or almost all of them suffer from one or more disadvantage. Therefore, there is still a need to provide apparatus and methods for shielding high-pressure fluid devices.